Uploaded February 2020 | Updated September 2026, 2 weeks ago
The secret of a paper cup…
Equipment: drain cleaner, glass cup, paper cup, plastic stick.
Pour some drain cleaner into a glass and immerse a paper cup in it. After an hour, take the cup out and use a plastic stick to clean off the yellowed paper and reveal… plastic!
The sodium hydroxide in the drain cleaner destroys the paper’s structure, making it easy to clean away. This reveals the plastic film under it, which prevents the paper from getting wet and the beverage from leaking. The film is made of polyethylene, so this "paper" cup can not be recycled with regular paper. It requires separate collection and special processing.
Cool experiments are waiting for you in the MEL Chemistry subscription!
Safety precautions: Warning! Only under adult supervision.
The secret of a paper cup…
Equipment: drain cleaner, glass cup, paper cup, plastic stick.
Pour some drain cleaner into a glass and immerse a paper cup in it. After an hour, take the cup out and use a plastic stick to clean off the yellowed paper and reveal… plastic!
The sodium hydroxide in the drain cleaner destroys the paper’s structure, making it easy to clean away. This reveals the plastic film under it, which prevents the paper from getting wet and the beverage from leaking. The film is made of polyethylene, so this "paper" cup can not be recycled with regular paper. It requires separate collection and special processing.
Cool experiments are waiting for you in the MEL Chemistry subscription!
Safety precautions: Warning! Only under adult supervision.









![Chemical clock
Chemists are so punctual – they’ve even designed a chemical clock!
Hydrogen peroxide is a very active compound and can be both an oxidizer and a reducing agent. In this process, it reduces iodic acid to form molecular iodine and a so-called triiodide complex. This process can be simplified to the following chemical reactions:
HIO₃ + 3H₂O₂ → HI + 3O₂↑ + 3H₂O
5HI + HIO₃ → 3I₂ + 3H₂O
HI + I₂ → H[I₃]
Since oxygen is formed during the first reaction, we can observe the emergence of the gas. The iodine and triiodide complex turn the solution amber. But the solution immediately turns blue, since the starch molecules, which are very long and look like spirals, trap iodine molecules like a fishnet, forming a deep blue iodine-starch complex. Under the action of malonic acid, this complex is destroyed, since it reduces iodine molecules, while the solution itself becomes colorless:
C₃H₄O₄ + I₂ → C₃H₃O₄I + HI
The process repeats every few seconds, and the reaction period depends on the concentrations of the initial solutions. What is this if not a chemical clock?
Fun and safe experiments await you in the MEL Chemistry subscription!
Attention! All experiments are performed by professionals. Do not attempt. Chemical clock](https://i.ytimg.com/vi/ZhBNZV15uy0/mqdefault.jpg)
